I once worked as an assistant biologist on a wildlife project in the Badlands National Park (South Dakota). Much of my time involved studying Prairie Dogs, including those above. The one on the left was a frequent visitor to my live traps, which I used to capture prairie dogs for acquiring blood samples. Once an individual had been sampled, however, it could not be sampled again and was released without giving blood. Some prairie dogs figured this out and allowed themselves to be trapped again and again, simply for the pleasure of eating the bait within. Biologists have a term for this - "Trap Happy".
The picture was shot using my Nikon FM and a 300mm Nikon lens.